In a capillary electrophoresis device in general, a fused silica capillary having 100 μm or less in inner diameter is filled up with a separation medium (an electrophoresis buffer solution or an electrophoresis buffer solution containing a sieving polymer solution), and a sample is introduced into one end of the capillary, after which a voltage is applied to both ends of the capillary to perform an electrophoresis of the sample within the capillary so as to separate [the sample]. The temperature in the periphery of the capillary is kept constant for the stabilization of the separation performance in the capillary. The analyte component separated in the capillary is detected on the other end side of the capillary by other optical or electrochemical fluorescence technique. The capillary electrophoresis device may have one capillary or a plurality of capillaries mounted.
The plate used for an electrophoresis is equipped with, for example, a substrate provided with an electrophoresis flow path in the inside; and a pair of reservoirs that are arranged at both ends of the electrophoresis flow path, used for storing an electrophoresis buffer solution, and electrically conducted to the end part of the electrophoresis flow path via the electrophoresis buffer solution (see Patent Literature 1). One or a plurality of electrophoresis flow paths may be provided to one substrate.
There is an electric injection method (an electrokinetic injection method: EKI method) as one of the methods of introducing a sample to a flow path formed in a capillary or a plate (for example, see Non-Patent Literature 1). In the electric injection method, a voltage for a certain period of time is applied to two electrodes, in a state where one end (injection end) of the electrophoresis flow path filled up with a separation medium is brought in contact with a sample, while the other end of the electrophoresis flow path is brought in contact with a buffer solution, and the electrodes are brought in contact with each of the sample and the buffer solution, thereby introducing the sample of a specified quantity into the flow path.
After the sample is introduced into the electrophoresis flow path, the electrophoresis of the sample is performed by bringing the sample injection end in contact with the buffer solution, immersing the electrodes in the buffer solution in each reservoir provided at both ends of the electrophoresis flow path, and applying a voltage to the two electrodes.